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From:   Doug Anderson <dianders@chromium.org>
Date:   Thu, 27 Feb 2020 14:06:44 -0800
Message-ID: <CAD=FV=UutvJE+k4W0sQDs6q+oOfbz5Tz670+L-8fFHfdB=KytQ@mail.gmail.com>
Subject: Re: [RFT PATCH 2/4] usb: dwc2: Do not update data length if it is 0
 on inbound transfers
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Minas Harutyunyan <hminas@synopsys.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?B?QW50dGkgU2VwcMOkbMOk?= <a.seppala@gmail.com>,
        Boris ARZUR <boris@konbu.org>, linux-usb@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Felipe Balbi <balbi@kernel.org>,
        Stefan Wahren <stefan.wahren@i2se.com>,
        Martin Schiller <ms@dev.tdt.de>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi,

On Wed, Feb 26, 2020 at 1:04 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> The DWC2 documentation states that transfers with zero data length should
> set the number of packets to 1 and the transfer length to 0. This is not
> currently the case for inbound transfers: the transfer length is set to
> the maximum packet length. This can have adverse effects if the chip
> actually does transfer data as it is programmed to do. Follow chip
> documentation and keep the transfer length set to 0 in that situation.
>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/usb/dwc2/hcd.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)

I don't have any other test setup that you don't have, so just giving
my review tag and not tested tag.

I will note that it feels like this should have a "Fixes" tag or a
direct Cc to stable to make it obvious that it should make its way
back to stable trees.

Reviewed-by: Douglas Anderson <dianders@chromium.org>